1. Field of the Invention
The present invention relates to a wheel suspension of a vehicle such as an automobile, and more particularly, to a wheel suspension for mounting a wheel to a vehicle body with high stability of toe adjustment while allowing bounding and rebounding of the rear wheel relative to the vehicle body.
2. Description of the Prior Art
A problem by nature of the wishbone type wheel suspension is that even a very small relative shifting between the pivot centers of the mutually pivoting members at each pivot point in the suspension due to certain resiliency of a bush element or the like incorporated in the pivot point could induce a relatively large deviation of the toe adjustment of the wheel supported by the suspension. Additional reinforcing members such as a control rod or a tie rod have been incorporated in the wishbone type suspensions. However, the conventional combinations of a wishbone member and a control rod or a tie rod do not appear to be completely satisfactory with regard to the stability of toe adjustment.
In the conventional combinations of a wishbone member and a control rod or a tie rod, a wheel supporting member such a spindle or a wheel axle bearing is primarily supported from the vehicle body by a wishbone member, or a set of upper wishbone member and a lower wishbone member in the double wishbone type suspension, and a control rod or a tie rod is mounted generally in parallel with the wishbone member on the front side or the rear side of the wishbone member or members so as to serve as a horizontal strut member for restricting casual turns of the wheel in toe changing directions. However, since the control rod or the tie rod is pivotably connected at opposite ends thereof with the vehicle body and the wheel supporting member via a bush or the like in order to allow bounding and rebounding movement of the wheel relative to the vehicle body, the combination of the wishbone member and the control rod or the tie rod form a parallelogrammic frame structure with a part of the vehicle body and the wheel supporting member, said parallelogrammic frame structure being flexible at the four corners thereof. Of course the shape of parallelogram is not fixed only by the length of the four sides.
An A-type arm is known in the wishbone type wheel suspension. It is constructed to have a pair of leg portions integrally joined at one end of each leg portion and is generally pivotably connected at two foot ends thereof with the vehicle body and at an apex end thereof with the wheel supporting member. In such a suspension structure, although the A-type arm itself has a triangular and therefore geometrically fixed shape, the rigidity of the triangular structure does not contribute to the toe holding stability of the wheel mounted to the apex point of the triangle. When a control rod or a tie rod is combined with such an A-type arm, it results again in a parallelogrammic structure.